Invasive lobular carcinoma (ILC) is recognized in its classical form and as variants with tubulo-lobular, solid, pleomorphic, alveolar or signet ring cell differentiation. The most common classical form differs from invasive ductal carcinoma (IDC) by its slower tumor proliferation and less common axillary metastases. When compared stage by stage, long term prognosis is similar to IDC, however. Prognostic subtyping of ILC can be achieved by the recognition of variant forms and mitotic counting. The combination of these factors may be used for tumor grading (5-year survival 100% with grade 1 vs. 82% with grade 2, and 57% with grade 3, n = 241). The detailed histopathologic diagnosis therefore permits prognostic assessment also in ILC.